The present invention relates to a heat exchanger of the general type having a plurality of tubes of generally rectangular or oval cross section, which run parallel to one another and have a longitudinal side and a narrow side; a first collecting tank attached to the tubes at a first end of each tube; and heat exchange ribs bearing on the tubes. The invention also relates to a method for producing a heat exchanger and to an arrangement of a first heat exchanger in relation to a second heat exchanger.
It is known that a heat exchanger consists of a tube bundle of rectangular or flatly oval tubes, ribs or fins being arranged between the tubes. At the opposite tube ends, the tubes are enclosed in a header or tube frame. This header has in the longitudinal direction, at each edge, a projecting U-shaped collar for receiving the hood-shaped collecting tank or header tank. After the tube ends have been connected to the header, the collecting tank is placed with its legs onto the U-shaped collar of the header and is flanged to the latter. One disadvantage of the known head exchanger is that the projecting design of the header makes an increased space requirement necessary for the heat exchanger.
German Offenlegungsschrift No. 26 11 397 discloses a heat exchanger, in which the tubes running parallel bear on one another and are welded together in the region of the tube ends by means of connecting surfaces in each case. A disadvantage of this known heat exchanger, however, is that the tube ends are enclosed in a frame which projects at the edge. The design of the known heat exchanger consequently cannot lead to a reduction in its space requirement.
Therefore, one object of the present invention is to provide an improved heat exchanger design. A further object of the invention resides in the provision of an improved arrangement of heat exchangers. Still another object of the invention is to provide an improved method for producing a heat exchanger, such that heat exchangers can be produced in a simple way and cost-effectively, along with a low space requirement.
In accomplishing these and other objects, there has been provided according to one aspect of the present invention a heat exchanger comprising: a plurality of tubes of generally rectangular or oval cross section, which run parallel to one another and have a longitudinal side and a narrow side; a first collecting tank attached to the tubes at a first end of each tube; and heat exchange ribs bearing on the tubes, wherein the tubes are expanded at the tube ends in a direction perpendicular to the longitudinal side to form at least one generally planar first connecting surface for bearing on and being connected to an adjacent connecting surface of the tube end of an adjacent tube, and wherein at least one narrow side of the tube end forms a second connecting surface for connection to the collecting tank.
In accordance with another aspect of the invention, there has been provided a method for producing a heat exchanger of according to the invention, comprising: transversely expanding the tube ends relative to the longitudinal direction of the tubes to form tube ends of rectangular cross section; placing either a performed collecting tank or a bracket for receiving a collecting tank onto a tube bundle formed from the parallel tubes and from the ribs, this tank or bracket having leg ends bearing on the second connecting surfaces; and then simultaneously brazing the first connecting surfaces of the adjacent tube ends and the second connecting surfaces to the leg ends.
In accordance with still another aspect of the invention, there has been provided an arrangement of a first head exchanger of the type according to the invention, relative to a second heat exchanger, wherein the first heat exchanger is connected to the second heat exchanger by a connecting element extending from the collecting tank of the first heat exchanger to an adjacent collecting tank of the second heat exchanger.
Further objects, features and advantages of the present invention will become apparent from the detailed description of preferred embodiments that follows, when considered together with the attached figures of drawing.